HAST.CONF(5) FreeBSD File Formats Manual HAST.CONF(5)
NAME
hast.conf - configuration file for the hastd(8) daemon and the hastctl(8)
utility
DESCRIPTION
The hast.conf file is used by both hastd(8) daemon and hastctl(8) control
utility. Configuration file is designed in a way that exactly the same
file can be (and should be) used on both HAST nodes. Every line starting
with # is treated as comment and ignored.
CONFIGURATION FILE SYNTAX
General syntax of the hast.conf file is following:
# Global section
control <addr>
listen <addr>
replication <mode>
checksum <algorithm>
compression <algorithm>
timeout <seconds>
exec <path>
metaflush on | off
pidfile <path>
on <node> {
# Node section
control <addr>
listen <addr>
pidfile <path>
}
on <node> {
# Node section
control <addr>
listen <addr>
pidfile <path>
}
resource <name> {
# Resource section
replication <mode>
checksum <algorithm>
compression <algorithm>
name <name>
local <path>
timeout <seconds>
exec <path>
metaflush on | off
on <node> {
# Resource-node section
name <name>
# Required
local <path>
metaflush on | off
# Required
remote <addr>
source <addr>
}
on <node> {
# Resource-node section
name <name>
# Required
local <path>
metaflush on | off
# Required
remote <addr>
source <addr>
}
}
Most of the various available configuration parameters are optional. If
parameter is not defined in the particular section, it will be inherited
from the parent section. For example, if the listen parameter is not
defined in the node section, it will be inherited from the global
section. In case the global section does not define the listen parameter
at all, the default value will be used.
CONFIGURATION FILE DESCRIPTION
The <node> argument can be replaced either by a full hostname as obtained
by gethostname(3), only first part of the hostname, by node's UUID as
found in the kern.hostuuid sysctl(8) variable or by node's hostid as
found in the kern.hostid sysctl(8) variable.
The following statements are available:
control <addr>
Address for communication with hastctl(8). Each of the following
examples defines the same control address:
uds:///var/run/hastctl
unix:///var/run/hastctl
/var/run/hastctl
The default value is uds:///var/run/hastctl.
pidfile <path>
File in which to store the process ID of the main hastd(8) process.
The default value is /var/run/hastd.pid.
listen <addr>
Address to listen on in form of:
protocol://protocol-specific-address
Each of the following examples defines the same listen address:
0.0.0.0
0.0.0.0:8457
tcp://0.0.0.0
tcp://0.0.0.0:8457
tcp4://0.0.0.0
tcp4://0.0.0.0:8457
Multiple listen addresses can be specified. By default hastd
listens on tcp4://0.0.0.0:8457 and tcp6://[::]:8457 if kernel
supports IPv4 and IPv6 respectively.
replication <mode>
Replication mode should be one of the following:
memsync
Report the write operation as completed when local write
completes and when the remote node acknowledges the data
receipt, but before it actually stores the data. The data on
remote node will be stored directly after sending
acknowledgement. This mode is intended to reduce latency,
but still provides a very good reliability. The only
situation where some small amount of data could be lost is
when the data is stored on primary node and sent to the
secondary. Secondary node then acknowledges data receipt and
primary reports success to an application. However, it may
happen that the secondary goes down before the received data
is really stored locally. Before secondary node returns,
primary node dies entirely. When the secondary node comes
back to life it becomes the new primary. Unfortunately some
small amount of data which was confirmed to be stored to the
application was lost. The risk of such a situation is very
small. The memsync replication mode is the default.
fullsync
Mark the write operation as completed when local as well as
remote write completes. This is the safest and the slowest
replication mode.
async
The write operation is reported as complete right after the
local write completes. This is the fastest and the most
dangerous replication mode. This mode should be used when
replicating to a distant node where latency is too high for
other modes.
checksum <algorithm>
Checksum algorithm should be one of the following:
none No checksum will be calculated for the data being send over
the network. This is the default setting.
crc32 CRC32 checksum will be calculated.
sha256 SHA256 checksum will be calculated.
compression <algorithm>
Compression algorithm should be one of the following:
none Data send over the network will not be compressed.
hole Only blocks that contain all zeros will be compressed. This
is very useful for initial synchronization where potentially
many blocks are still all zeros. There should be no
measurable performance overhead when this algorithm is being
used. This is the default setting.
lzf The LZF algorithm by Marc Alexander Lehmann will be used to
compress the data send over the network. LZF is very fast,
general purpose compression algorithm.
timeout <seconds>
Connection timeout in seconds. The default value is 20.
exec <path>
Execute the given program on various HAST events. Below is the
list of currently implemented events and arguments the given
program is executed with:
<path> role <resource> <oldrole> <newrole>
Executed on both primary and secondary nodes when resource
role is changed.
<path> connect <resource>
Executed on both primary and secondary nodes when connection
for the given resource between the nodes is established.
<path> disconnect <resource>
Executed on both primary and secondary nodes when connection
for the given resource between the nodes is lost.
<path> syncstart <resource>
Executed on primary node when synchronization process of
secondary node is started.
<path> syncdone <resource>
Executed on primary node when synchronization process of
secondary node is completed successfully.
<path> syncintr <resource>
Executed on primary node when synchronization process of
secondary node is interrupted, most likely due to secondary
node outage or connection failure between the nodes.
<path> split-brain <resource>
Executed on both primary and secondary nodes when split-brain
condition is detected.
The <path> argument should contain full path to executable program.
If the given program exits with code different than 0, hastd will
log it as an error.
The <resource> argument is resource name from the configuration
file.
The <oldrole> argument is previous resource role (before the
change). It can be one of: init, secondary, primary.
The <newrole> argument is current resource role (after the change).
It can be one of: init, secondary, primary.
metaflush on | off
When set to on, flush write cache of the local provider after every
metadata (activemap) update. Flushing write cache ensures that
provider will not reorder writes and that metadata will be properly
updated before real data is stored. If the local provider does not
support flushing write cache (it returns EOPNOTSUPP on the
BIO_FLUSH request), hastd will disable metaflush automatically.
The default value is on.
name <name>
GEOM provider name that will appear as /dev/hast/<name>. If name
is not defined, resource name will be used as provider name.
local <path>
Path to the local component which will be used as backend provider
for the resource. This can be either GEOM provider or regular
file.
remote <addr>
Address of the remote hastd daemon. Format is the same as for the
listen statement. When operating as a primary node this address
will be used to connect to the secondary node. When operating as a
secondary node only connections from this address will be accepted.
A special value of none can be used when the remote address is not
yet known (eg. the other node is not set up yet).
source <addr>
Local address to bind to before connecting to the remote hastd
daemon. Format is the same as for the listen statement.
FILES
/etc/hast.conf The default hastctl(8) and hastd(8) configuration file.
/var/run/hastctl Control socket used by the hastctl(8) control utility
to communicate with the hastd(8) daemon.
EXAMPLES
The example configuration file can look as follows:
listen tcp://0.0.0.0
on hasta {
listen tcp://2001:db8::1/64
}
on hastb {
listen tcp://2001:db8::2/64
}
resource shared {
local /dev/da0
on hasta {
remote tcp://10.0.0.2
}
on hastb {
remote tcp://10.0.0.1
}
}
resource tank {
on hasta {
local /dev/mirror/tanka
source tcp://10.0.0.1
remote tcp://10.0.0.2
}
on hastb {
local /dev/mirror/tankb
source tcp://10.0.0.2
remote tcp://10.0.0.1
}
}
SEE ALSO
gethostname(3), geom(4), hastctl(8), hastd(8)
AUTHORS
The hast.conf was written by Pawel Jakub Dawidek <pjd@FreeBSD.org> under
sponsorship of the FreeBSD Foundation.
FreeBSD 15.1-STABLE-HBSD January 25, 2012 HAST.CONF(5)